Influence of proinflammatory cytokines on neutrophil apoptosis. Freshly isolated neutrophils (1 × 106/mL) from healthy humans (control; ▪), and patients with severe sepsis (patient; □), were incubated during 16 hours with various recombinant human proinflammatory cytokines: IL-1β (2.5 ng/mL), IL-2 (20 ng/mL), IL-6 (1,000 U/mL), IL-8 (20 ng/mL), IL-12p70 (20 ng/mL), TNF-α (1,000 U/mL), IFN-γ (10 ng/mL), G-CSF (10 ng/mL), GM-CSF (10 ng/mL). Neutrophil apoptosis was analyzed by flow cytometry after permeabilization with ethanol and staining with propidium iodide. Data are reported as the percentage of fragmented nuclei reflecting the relative proportion of apoptotic cells. Results represent the mean ± SEM of five separate experiments performed with neutrophils isolated from five independent healthy individuals and five patients with severe sepsis. *P < .05 cytokine-treated versus untreated cells.
